One wonky approach might be to introduce some form of government seizure over time, like a scaling progressive rule based on the quantity of property owned that is actually a forced sale to the local housing authority. So over a period the extra housing equity would be owned by the authority and redistributed, while the existing homeowner gets cash but not the property. This particular concept feels flawed but something which produces wins all around is easier to get moving.
As for building the movement, a crisp rallying cry and lines of communication to local stakeholders is key. You probably need to search around for the location with the right mixture of local activism and receptive leadership, in the same way that many startups benefit from specific locations.